DOC: Adding a what's new entry for the norm callback

greglucas · greglucas · commit 3c6e144fb308 · 2021-03-20T08:26:59.000-06:00
diff --git a/doc/users/next_whats_new/callbacks_on_norms.rst b/doc/users/next_whats_new/callbacks_on_norms.rst
@@ -0,0 +1,7 @@
+A callback registry has been added to Normalize objects
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+`.colors.Normalize` objects now have a callback registry, ``callbacksNorm``,
+that can be connected to by other objects to be notified when the norm is
+updated. `.cm.ScalarMappable` is now a listener and will register a change
+when the norm's vmin, vmax or other attributes are changed.
